rustfmt_nightly: query stack during panic: end of query stack

[mzacho]

Hi,

When attempting to run cargo fmt on a the ill-typed (or maybe not even parsable?) library consisting of two files:

lib.rs:

mod foo;

foo.rs

const BAR = 42;

the compiler unexpectedly panics due to a failed assertion:

thread 'main' panicked at compiler/rustc_errors/src/lib.rs:565:9:
assertion failed: self.stashed_diagnostics.is_empty()

with rustc 1.78.0-nightly (fc3800f65 2024-02-26). Full stack-trace:

rustc-ice-2024-02-27T19_28_13-1514879.txt

I'm happy to work on this, but I'm a bit clueless as to what the issue is.

[calebcartwright]

Thanks for the report, wondering if this is related to (#6082, https://github.com/rust-lang/rust/pull/121487) and fixed by https://github.com/rust-lang/rust/pull/121301

[nnethercote]

https://github.com/rust-lang/rust/pull/121487 should fix this.

[ytmimi]

@mzacho when you have a moment could you double check if this is resolved on the latest nightly?

[wmmc88]

@ytmimi not OP, but i just checked on latest nightly (1.78.0-nightly (b6d2d841b 2024-03-05)) and I still have rustfmt crashing, although the stack is different:

thread 'main' panicked at src\tools\rustfmt\src\parse\session.rs:40:9:
silent emitter attempted to translate a diagnostic
stack backtrace:
   0:     0x7ff8f04d3641 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1e8839368d0f8ea2
   1:     0x7ff8f0505a3b - core::fmt::write_internal::h7df84b0bd19a91fc
   2:     0x7ff8f04c9c8a - <std::io::IoSlice as core::fmt::Debug>::fmt::h40bb585663c296ad
   3:     0x7ff8f04d346a - std::sys_common::backtrace::lock::haaab04a5a6ea97f3
   4:     0x7ff8f04d660f - std::panicking::default_hook::h20b56c3ef0f4d280
   5:     0x7ff8f04d62b9 - std::panicking::default_hook::h20b56c3ef0f4d280
   6:     0x7ff8f4ef90c5 - <wasmparser[386d3e72a2020ab8]::validator::names::ComponentName as core[740ffb2decc37d3]::fmt::Debug>::fmt
   7:     0x7ff8f04d6c33 - std::panicking::rust_panic_with_hook::h3af291445738d743
   8:     0x7ff8f04d6a9b - <std::panicking::begin_panic_handler::StaticStrPayload as core::panic::PanicPayload>::take_box::h3fc74e926739df0e
   9:     0x7ff8f04d3f49 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1e8839368d0f8ea2
  10:     0x7ff8f04d6786 - rust_begin_unwind
  11:     0x7ff8f052c2a7 - core::panicking::panic_fmt::hf6c7b67361c454bc
  12:     0x7ff6910a649e - <unknown>
  13:     0x7ff6910a4108 - <unknown>
  14:     0x7ff8f626154c - <rustc_parse[f5edc4ae78f12cf2]::parser::diagnostics::UnaryFixity as core[740ffb2decc37d3]::fmt::Display>::fmt
  15:     0x7ff8f6208f30 - <rustc_parse[f5edc4ae78f12cf2]::errors::ExpectedIdentifierFound>::new
  16:     0x7ff8f4d0612f - <rustc_parse[f5edc4ae78f12cf2]::parser::expr::CondChecker as rustc_ast[973cc0afb5b54271]::mut_visit::MutVisitor>::visit_expr
  17:     0x7ff8f4bea15e - <rustc_ast_passes[8fab3d9e89b724a7]::ast_validation::AstValidator as rustc_ast[973cc0afb5b54271]::visit::Visitor>::visit_assoc_item
  18:     0x7ff8f4bea2ef - <rustc_ast_passes[8fab3d9e89b724a7]::ast_validation::AstValidator as rustc_ast[973cc0afb5b54271]::visit::Visitor>::visit_assoc_item
  19:     0x7ff8f3c9af20 - rustc_ast_passes[8fab3d9e89b724a7]::ast_validation::check_crate
  20:     0x7ff8f3cc6b99 - rustc_parse[f5edc4ae78f12cf2]::parser::attr_wrapper::has_cfg_or_cfg_attr
  21:     0x7ff8f3c9b98a - rustc_parse[f5edc4ae78f12cf2]::source_file_to_stream
  22:     0x7ff8f3c9b70e - rustc_parse[f5edc4ae78f12cf2]::new_parser_from_file
  23:     0x7ff8f3c9b3b0 - rustc_parse[f5edc4ae78f12cf2]::maybe_new_parser_from_source_str
  24:     0x7ff6910c8380 - <unknown>
  25:     0x7ff690ff8807 - <unknown>
  26:     0x7ff691087508 - <unknown>
  27:     0x7ff690ffbf08 - <unknown>
  28:     0x7ff691073f87 - <unknown>
  29:     0x7ff6910750c5 - <unknown>
  30:     0x7ff69108f1ce - <unknown>
  31:     0x7ff69108bcb1 - <unknown>
  32:     0x7ff6911894f3 - <unknown>
  33:     0x7ff69111638b - <unknown>
  34:     0x7ff6911042e9 - <unknown>
  35:     0x7ff6910ffa9c - <unknown>
  36:     0x7ff6910f6f36 - <unknown>
  37:     0x7ff691100d62 - <unknown>
  38:     0x7ff6910f6f36 - <unknown>
  39:     0x7ff691100d62 - <unknown>
  40:     0x7ff6910f6f36 - <unknown>
  41:     0x7ff6911056ba - <unknown>
  42:     0x7ff690f8258a - <unknown>
  43:     0x7ff690f88253 - <unknown>
  44:     0x7ff690f857b3 - <unknown>
  45:     0x7ff690f7bcfd - <unknown>
  46:     0x7ff690f6afd3 - <unknown>
  47:     0x7ff690f856ef - <unknown>
  48:     0x7ff690f68f0a - <unknown>
  49:     0x7ff690f668d8 - <unknown>
  50:     0x7ff690f8f136 - <unknown>
  51:     0x7ff690f75aac - <unknown>
  52:     0x7ff8f04bbfb2 - std::rt::lang_start_internal::h59f7001875d06b74
  53:     0x7ff690f6becc - <unknown>
  54:     0x7ff6912fa71c - <unknown>
  55:     0x7ff995dd257d - BaseThreadInitThunk
  56:     0x7ff99704aa58 - RtlUserThreadStart

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rustfmt/issues/new?labels=bug

note: please attach the file at `D:\git-repos\github\windows-drivers-rs.git\worktrees-folder\better-macro-must-use\rustc-ice-2024-03-06T01_42_41-10216.txt` to your bug report

query stack during panic:
end of query stack

rustc-ice-2024-03-06T01_42_41-10216.txt:

thread 'main' panicked at src\tools\rustfmt\src\parse\session.rs:40:9:
silent emitter attempted to translate a diagnostic
stack backtrace:
   0:     0x7ff8f04bd764 - std::backtrace::Backtrace::force_capture::h7ea177fe0a8bf95d
   1:     0x7ff8f04bd6c4 - std::backtrace::Backtrace::force_capture::h7ea177fe0a8bf95d
   2:     0x7ff8f4ef9233 - <wasmparser[386d3e72a2020ab8]::validator::names::ComponentName as core[740ffb2decc37d3]::fmt::Debug>::fmt
   3:     0x7ff8f04d6c33 - std::panicking::rust_panic_with_hook::h3af291445738d743
   4:     0x7ff8f04d6a9b - <std::panicking::begin_panic_handler::StaticStrPayload as core::panic::PanicPayload>::take_box::h3fc74e926739df0e
   5:     0x7ff8f04d3f49 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h1e8839368d0f8ea2
   6:     0x7ff8f04d6786 - rust_begin_unwind
   7:     0x7ff8f052c2a7 - core::panicking::panic_fmt::hf6c7b67361c454bc
   8:     0x7ff6910a649e - <unknown>
   9:     0x7ff6910a4108 - <unknown>
  10:     0x7ff8f626154c - <rustc_parse[f5edc4ae78f12cf2]::parser::diagnostics::UnaryFixity as core[740ffb2decc37d3]::fmt::Display>::fmt
  11:     0x7ff8f6208f30 - <rustc_parse[f5edc4ae78f12cf2]::errors::ExpectedIdentifierFound>::new
  12:     0x7ff8f4d0612f - <rustc_parse[f5edc4ae78f12cf2]::parser::expr::CondChecker as rustc_ast[973cc0afb5b54271]::mut_visit::MutVisitor>::visit_expr
  13:     0x7ff8f4bea15e - <rustc_ast_passes[8fab3d9e89b724a7]::ast_validation::AstValidator as rustc_ast[973cc0afb5b54271]::visit::Visitor>::visit_assoc_item
  14:     0x7ff8f4bea2ef - <rustc_ast_passes[8fab3d9e89b724a7]::ast_validation::AstValidator as rustc_ast[973cc0afb5b54271]::visit::Visitor>::visit_assoc_item
  15:     0x7ff8f3c9af20 - rustc_ast_passes[8fab3d9e89b724a7]::ast_validation::check_crate
  16:     0x7ff8f3cc6b99 - rustc_parse[f5edc4ae78f12cf2]::parser::attr_wrapper::has_cfg_or_cfg_attr
  17:     0x7ff8f3c9b98a - rustc_parse[f5edc4ae78f12cf2]::source_file_to_stream
  18:     0x7ff8f3c9b70e - rustc_parse[f5edc4ae78f12cf2]::new_parser_from_file
  19:     0x7ff8f3c9b3b0 - rustc_parse[f5edc4ae78f12cf2]::maybe_new_parser_from_source_str
  20:     0x7ff6910c8380 - <unknown>
  21:     0x7ff690ff8807 - <unknown>
  22:     0x7ff691087508 - <unknown>
  23:     0x7ff690ffbf08 - <unknown>
  24:     0x7ff691073f87 - <unknown>
  25:     0x7ff6910750c5 - <unknown>
  26:     0x7ff69108f1ce - <unknown>
  27:     0x7ff69108bcb1 - <unknown>
  28:     0x7ff6911894f3 - <unknown>
  29:     0x7ff69111638b - <unknown>
  30:     0x7ff6911042e9 - <unknown>
  31:     0x7ff6910ffa9c - <unknown>
  32:     0x7ff6910f6f36 - <unknown>
  33:     0x7ff691100d62 - <unknown>
  34:     0x7ff6910f6f36 - <unknown>
  35:     0x7ff691100d62 - <unknown>
  36:     0x7ff6910f6f36 - <unknown>
  37:     0x7ff6911056ba - <unknown>
  38:     0x7ff690f8258a - <unknown>
  39:     0x7ff690f88253 - <unknown>
  40:     0x7ff690f857b3 - <unknown>
  41:     0x7ff690f7bcfd - <unknown>
  42:     0x7ff690f6afd3 - <unknown>
  43:     0x7ff690f856ef - <unknown>
  44:     0x7ff690f68f0a - <unknown>
  45:     0x7ff690f668d8 - <unknown>
  46:     0x7ff690f8f136 - <unknown>
  47:     0x7ff690f75aac - <unknown>
  48:     0x7ff8f04bbfb2 - std::rt::lang_start_internal::h59f7001875d06b74
  49:     0x7ff690f6becc - <unknown>
  50:     0x7ff6912fa71c - <unknown>
  51:     0x7ff995dd257d - BaseThreadInitThunk
  52:     0x7ff99704aa58 - RtlUserThreadStart

rustc version: 1.78.0-nightly (b6d2d841b 2024-03-05)
platform: x86_64-pc-windows-msvc

[ytmimi]

@wmmc88 thanks for taking the time to look into this. I believe we're still waiting on #6082 to be resolved. I'm hopeful that https://github.com/rust-lang/rust/pull/121301 will fix the issue on nightly once it's merged 🤞🏼

[ytmimi]

@mzacho or @wmmc88 when either of you have a moment can you confirm if this is resolved with the latest nightly. I've been testing with the latest nightly (rustfmt 1.7.0-nightly (7d3702e4 2024-03-06)) and I think the panic is resolved 🎉. Would love some confirmation from someone on that as well.

steps to verify:

1. rustup install nightly or rustup install nightly-2024-03-07
2. rustfmt +nightly

[wmmc88]

@ytmimi Latest nightly cargo fmt works for me again. Thanks!

[ytmimi]

@namanlp since you reached out on Zulip I was wondering if you'd want to get a little hands on experience adding a quick test case for this issue to close it out? I can explain more of the details of what I'm thinking on Zulip if you're interested.

[namanlp]

Hi there,

I do understand the issue as well as the fix. Can you please tell me what to include in the test?

( I did see a few other tests to know how the tests should look in general )

Thank You

[ytmimi]

@namanlp normally test cases are added to the tests/source directory, and formatted code is added to tests/target with the same name.

This one is a little different because const BAR = 42; will be rejected by the parser. You should see a similar error message if you run rustfmt on that input:

error: missing type for `const` item
 --> <stdin>:1:10
  |
1 | const BAR = 42;
  |          ^ help: provide a type for the item: `: <type>`

You should be able to add another parser error test to src/test/parser.rs

[namanlp]

Hi @ytmimi ,

Yes, I can see that error.

So, as per my understanding, I have to add the test files to tests/parser , and then, add a similar driver code here src/test/parser.rs

Is that ok?

[mzacho]

@mzacho when you have a moment could you double check if this is resolved on the latest nightly?

Confirmed on nightly-2024-03-10.

@namanlp I think you can do something similar to the test that's in place for issue-4126 (in tests/parser/issue-4126 and src/test/parser.rs, yes)

[ytmimi]

@mzacho thanks for confirming!

---

So, as per my understanding, I have to add the test files to tests/parser , and then, add a similar driver code here src/test/parser.rs

Is that ok?

@namanlp Yup, that should be it. I'd take a similar approach to the other tests in src/test/parser.rs

If you want, you can also add the code snippet from https://github.com/rust-lang/rustfmt/issues/6082#issuecomment-1952590404 as a separate test case, which deals with the same issue and contains a complete code snippet without any parse errors. No problem if not. If you choose to also include that code snippet all you'd need to do is add it to a file in the tests/target directory, which is typically what you'd do when adding test cases to rustfmt.

[mzacho]

@namanlp are you still working on this? Otherwise I'd like to pick it up

[namanlp]

Hi, Sorry, this issue completely skipped out of my mind 😅

I will make a PR today.